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cifs: reduce roundtrips on create/qinfo requests
To work around some Window servers that return
STATUS_OBJECT_NAME_INVALID on query infos under DFS namespaces that
contain non-ASCII characters, we started checking for -ENOENT on every
file open, and if so, then send additional requests to figure out
whether it is a DFS link or not. It means that all those requests
will be sent to every non-existing file.
So, in order to reduce the number of roundtrips, check earlier whether
status code is STATUS_OBJECT_NAME_INVALID and tcon supports dfs, and
if so, then map -ENOENT to -EREMOTE so mount or automount will take
care of chasing the DFS link -- if it isn't an DFS link, then -ENOENT
will be returned appropriately.
Before patch
SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
SMB2 228 Ioctl Request FSCTL_DFS_GET_REFERRALS, File: \ada.test\dfs\foo
SMB2 143 Ioctl Response, Error: STATUS_OBJECT_PATH_NOT_FOUND
SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
SMB2 228 Ioctl Request FSCTL_DFS_GET_REFERRALS, File: \ada.test\dfs\foo
SMB2 143 Ioctl Response, Error: STATUS_OBJECT_PATH_NOT_FOUND
After patch
SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
SMB2 438 Create Request File: ada.test\dfs\foo;GetInfo Request...
SMB2 310 Create Response, Error: STATUS_OBJECT_NAME_NOT_FOUND;...
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>